Data centers constantly face the ever-proliferating demand of data storage. Hard disks are one of the primary storage media utilized by data centers. However, hard disks are susceptible to a high annual fault rate (AFR) which leads to a considerable amount of volume non-utilized or underutilized. Conditions such as reaching system capacity, mechanical wear and degradation, as well as disk failure all contribute to the faulting states of HDDs.
One of the causing factors of disk failure is the medium error, which occurs when a disk sector cannot be read. One solution a storage system utilizes to address sector errors is to deploy a pending sector procedure, as shown in FIG. 1, where in response to a failure to read, the storage system marks the disk sector as pending sector after an number of unsuccessful retires and attempts to rectify the errors through internal recovering mechanisms. Given a pending status, upon a write operation to the particular pending disk sector, the storage system replaces the content of the pending disk sector with the content of the write operation. Subsequently, the data written to the pending disk sector is read for verification. Upon a verified write operation, the pending disk sector will be cleared of the pending status and become a normal functioning sector. The storage system also keeps a count of the pending disk sectors and in the event the count becomes greater than a pre-determined threshold, the storage system will mark the unreliable disk drive as a failed disk drive.
However, presently the pending sector procedure as described above is only initiated upon write operations to the pending sector. In other words, absent a data write event to the disk sector marked as pending, for example, when the storage system is servicing read intensive applications for an extended period of time, a problematic sector will never be rewritten and rectified as normal sector. Such a sector remains pending to the possible extent that the entire disk drive is marked as inaccessible due to a large number of sectors accumulated as pending in this fashion.
Therefore, there exists a need to effectively rectify a pending disk sector towards higher degree of disk reliability, fuller disk capacity usage and extended disk operating life.